A standard lock has a main actuator that is displaced by the appropriate key to displace a slide or bolt that is connected to the actuator by means of a linkage. Thus, for instance, the key is turned in a cylinder having an eccentric pin constituting the actuator. A gear wheel is driven by the eccentric actuator and a rack rod meshing with the gear wheel in turn operates the slide bolt, or even a plurality of slide bolts. Such a system is known for use in a heavy-duty system like a safety-deposit drawer or vault door.
Another type of lock is known where a motor is connected to the linkage and in turn is operated by an electrical controller which energizes the motor to operate the linkage when, for example, an appropriate PIN number is entered in a keypad or an appropriately coded card is swiped through a reader slot. This system can also be used to open a heavy-duty slide lock and is also frequently used on a hotel-room door.
The main disadvantage with the purely mechanical system is that the relatively small key must exert considerable force as torque to move all the various elements of the lock and open or close it. This is a particular problem with a multibolt lock assembly where the combined mass of the bolts and the linkages can be considerable. Thus in such arrangements it is relatively easy to break or bend the key.
While there is no such mechanical strain on the purely electrical systems, they are rendered inoperative when power fails. Furthermore they often require sophisticated electronics so that they are expensive.